Aqueous ink composition and method of recording using the same

ABSTRACT

A cyan ink comprising a phthalocyanine derivative represented by the following formula (I), excellent in color reproducibility, suitable for use in the ink jet recording method is disclosed. The combination use of this cyan ink comprising the phthalocyanine derivative with yellow and magenta inks, each comprising a specific dye, gives excellent color printing. ##STR1## wherein X represents an ion of a metal selected from Cu, Fe, Co and Ni, R 1  represents H or an alyl group, Z represents --O, --COOH or NR 2  R 3  (where R 2  represents H or an alkyl group, and R 3  represents an alkyl group or phenyl group), n represents an integer of 1 to 15, k and l represent 0 or 1, and m represents an integer of 1 to 4, provided that k, l and m fulfill the inequality 2≦k+1+m≦4.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink composition for recording, andto a method of recording, in particular, an ink jet recording method,using the same. More particularly, the present invention relates to anink composition comprising as a colorant a phthalocyanine derivative, toa method of recording, in particular, an ink jet recording method, usingthe same, and to a method for forming color images.

2. Background Art

Ink compositions are required to have various excellent properties.Specifically, they are not only required to have excellent colorreproducibility, but also required to produce images which are excellentin water resistance and light resistance.

Further, in the ink jet recording method in which droplets of an inkcomposition are ejected on a recording medium to form thereon an image,the ink composition is required to have much more excellent propertiesthan those required for ordinary writing utensils such as fountain pensand ball-point pens. For instance, the ink composition is required tohave a proper viscosity and a suitable surface tension, to be excellentin preservation stability, and not to cause clogging in a nozzle.

In general, many of these properties required for the ink compositionfor use in the ink jet recording method can be fulfilled by an aqueousink composition comprising a water-soluble dye water and a water-solubleorganic solvent. The properties of printed images, such as color tone,water resistance and light resistance, are highly dependent on the dyeused. It has been tried to utilize various dyes.

Ink compositions containing a phthalocyanine derivative as a cyan orblue dye have been proposed. For instance, the use of C. I. Direct Blue86, 87 or 199 has been proposed. Further, the use of a phthalocyaninederivative is also disclosed, for example, in Japanese Laid-Open PatentPublications Nos. 2772/1986, 149758/1987, 190273/1987 and 200883/1991.

However, there is yet room for improvement in these ink compositionscontaining a phthalocyanine derivative.

On the other hand, such a printer that produces color images by means ofthe ink jet printing method is also popular. Color images are formed byusing, in general, yellow, magenta and cyan ink compositions, andoptionally a black ink composition. By superposing these inkcompositions, red, green, and blue, and optionally black colors aredeveloped. In such color printing, each ink composition is required tobe highly reproducible in its own color. In addition to this, these inkcompositions are required to be excellent in reproducibility in red,green, and blue, and optionally black colors which are developed bysuperposing ink compositions one over another.

SUMMARY OF THE INVENTION

We have now found that an ink composition comprising as a colorant aspecific phthalocyanine derivative has extremely excellent properties.Furthermore, we have also found that excellent color printing can beobtained by the use of the combination of this cyan ink composition withyellow and magenta ink compositions, each comprising a specific dye.

Accordingly, an object of the present invention is to provide an inkcomposition having various properties which are required for inkcompositions.

Another object of the present invention is to provide an ink compositionhaving various properties which are required for ink compositions usefulfor ink jet recording.

A further object of the present invention is to provide a method ofprinting, in particular, an ink jet recording method, by which excellentcolor images can be obtained.

According to the present invention, there provides a cyan inkcomposition comprising as a colorant a phthalocyanine derivativerepresented by the following formula (I): ##STR2## wherein

X represents an ion of a metal selected from Cu, Fe, Co and Ni,

M represents hydrogen atom, an alkali metal, ammonium or an organicamine,

R¹ represents hydrogen atom or an alkyl group which may be substituted,

Z represents --OH, --COOH or NR² R³ ( where R² represents hydrogen atomor an alkyl group which may be substituted, and R³ represents an alkylgroup which may be substituted, or phenyl group which may besubstituted),

n represents an integer of 1 to 15,

k and l each independently represent 0 or 1, and

m represents an integer of 1 to 4,

provided that k, l and m fulfill the inequality 2≦k+l+m≦4.

According to the present invention, there provides a method in whichyellow, magenta and cyan ink compositions are used, wherein

the cyan ink composition comprises as a colorant the compoundrepresented by the above formula (I),

the yellow ink composition comprises as a colorant a compoundrepresented by the following formula (II): ##STR3## wherein

R⁴ and R⁵ each independently represent --OH; --SO₃ M; or phenyl ornaphthyl group substituted with --COOM,

R⁶ and R⁷ each independently represent hydrogen atom, an alkyl group oran alkoxy group,

R⁸ represents hydrogen atom, an alkyl group or a hydroxyalkyl group,

R⁹ represents hydrogen atom, --OH or a hydroxyalkyl group, and

M is as defined in the above formula (I), or a compound represented bythe following formula (III): ##STR4## wherein

R¹⁰ and R¹¹ each independently represent hydrogen atom, --OH or analkoxy group,

R¹² and R¹³ each independently represent hydrogen atom or an alkylgroup, and

M is as defined in the above formula (I), and

the magenta ink composition comprises as a colorant a compoundrepresented by the following formula (IV): ##STR5## wherein

R¹⁴ represents hydrogen atom or an alkyl group,

R¹⁵ represents hydrogen atom, a halogen atom or an alkyl group,

R¹⁶ represents --COOH or --SO₃ ⁻,

R¹⁷ and R¹⁸ each independently represent hydrogen atom, a halogen atom,an alkyl group or --SO₃ M, and

M is as defined in the above formula (I).

DETAILED DESCRIPTION OF THE INVENTION

Phthalocyanine Derivatives

The phthalocyanine derivative for use in the cyan ink compositionaccording to the present invention is a compound represented by theabove formula (I).

In the formula (I), hydrogen atoms on four benzene rings in thephthalocyanine skeleton are substituted with the groups --(SO₃ M)k,--(SO₂ NH₂)l and --(SO₂ --NR¹ --(CH₂)N--Z)m. While the position of thesubstitution is not particularly limited, among the above three groups,the group --(SO₂ --NR¹ --(CH₂)N--Z)m should exist in a number of atleast one. The above groups can exist in a number of four or less intotal. In other words, it is necessary that k and l represent an integerof 0 or 1, that m be an integer of 1 to 4, and that k, l and m be in therelationship which fulfills the inequality 2≦k+l+m≦4.

In the formula (I), X represents an ion of a metal selected from Cu, Fe,Co and Ni.

Specific examples of the alkali metal and the organic amine representedby M in the formula (I) include lithium, sodium, potassium, ammonium,dimethylammonium, morpholium and piperidinium.

The alkyl group represented by R¹ in the formula (I) is preferably alinear or branched C₁₋₄ alkyl group. One or more hydrogen atoms in thisalkyl group may be substituted, and preferable examples of thesubstituent include hydroxyl group and amino group.

In NR² R³ represented by Z in the formula (I), R² represents hydrogenatom or an alkyl group. This alkyl group is preferably a linear orbranched C₁₋₄ alkyl group. One or more hydrogen atoms in this alkylgroup may be substituted, and preferable examples of the substituentinclude hydroxyl group and amino group. Further, R³ represents an alkylgroup or phenyl group. This alkyl group is preferably a linear orbranched C₁₋₄ alkyl group. One or more hydrogen atoms in this alkylgroup may be substituted, and preferable examples of the substituentinclude hydroxyl group and amino group. Furthermore, one or morehydrogen atoms on the phenyl group may be substituted, and examples ofthe substituent include hydroxyl group and amino group.

In the formula (I), n represents an integer of 1 to 15. However, when Zis --COOH, n is preferably an integer of 2 to 12; and when Z is --OH, nis preferably an integer of 5 to 15.

Specific preferable examples of the phthalocyanine derivativerepresented by the formula (I) include the following compounds (I-1) to(I-16): ##STR6##

The compound having the formula (I) can be produced in accordance with aknown method for preparing a phthalocyanine derivative. For example thecompound (I) can be obtained in accordance with the method described inJapanese Laid-Open Patent Publication No. 22967/1984 or JapaneseLaid-Open Patent Publication No. 30874/1984.

The compound having the formula (I) can be produced by the followingmethod. The compound (I) can be prepared by reacting a compoundrepresented by the following formula (Va): ##STR7## wherein A representsthe group --(SO₃ M)k, --(SO₂ NH₂)l or --(SO₂ --NR¹ --(CH₂)N--Z)m (whereM, R¹, z, k, l and m are as defined in the formula (I)), and irepresents an integer of 1 to 4, or

a mixture of the compound (Va) and a compound represented by thefollowing formula (Vb): ##STR8## wherein B represents the group --(SO₃M)k, --(SO₂ NH₂)l or --(SO₂ --NR¹ --(CH₂)N--Z)m (where M, R¹, Z, k, land m are as defined in the formula (I)), and j represents an integer of1 to 4, with urea and a metal chloride represented by the formula XCln(where n agrees with the valency of X). In this reaction excessive ureadissolved may also play a role of a reaction solvent, and the reactioncan be carried out at a temperature of preferably about 190° to 200° C.

The values of k, l and m in the compound having the formula (I) can becontrolled by properly selecting the type and the mixing ratio of thecompounds (Va) and (Vb).

Further the compound (I) can be prepared from a compound of the formula(VIa): ##STR9## wherein A and i are as defined above, or the compound(VIa), and a compound of the formula (VIb): ##STR10## wherein B and jare as defined above, with a metal chloride represented by the formulaXCln (where n agrees with the valency of X). The reaction is carried outby:

(a) mixing these compounds and heating the mixture, for example, at atemperature of approximately 150° to 200° C., or

(b) heating the mixture at a temperature of approximately 190° to 200°C. in an inert solvent in the presence or absence of urea.

Also in this method, the values of k, l and m in the compound (I) can becontrolled by properly selecting the type and the mixing ratio of thecompounds (VIa) and (VIb).

The amount of the compound (I) to be incorporated into the inkcomposition can be properly determined depending upon the type of thesolvent component used, the properties required for the ink. However, inthe case where the ink composition will be used in the ink jet recordingmethod, the incorporation amount of the compound (I) is preferably from1.5 to 8.0% by weight, more preferably from 2.5 to 6.5% by weight of theink composition from the viewpoint of color tone.

Further, a mixture of water and a water-soluble organic solvent ispreferred as the solvent for use in ink composition of the presentinvention. Examples of this water-soluble organic solvent includepolyhydric alcohols such as ethylene glycol, diethylene glycol,triethylene glycol, polyethlene glycol, propylene glycol, 1,3-propanediol, 1,5-pentane diol, 1,2,6-hexane triol and glycerol; ethers ofpolyhydric alcohols such as ethylene glycol monomethyl ether, diethyleneglycol monobutyl ether, triethylene glycol monobutyl ether anddipropylene glycol monomethyl ether; nitrogen-containing solvents suchas formamides, dimethylformamide, diethanolamine, triethanolamine,1,3-dimethyl-2-imidazolidinone, 2-pyrrolidone andN-methyl-2-pyrrolidone; and sulfur-containing solvents such asthiodiglycol and dimethyl sulfoxide.

These solvents can be used either singly or as a mixture of two or more.The amount of the solvent is in the range of 3 to 40% by weight,preferably in the range of 3 to 30% by weight of ink composition fromthe view point of the prevention of clogging in a nozzle and the qualityof images printed.

Further, in order to enhance the drying characteristics of the ink afterthe formation of an image, it is preferable that the ink composition ofthe present invention further comprise a lower alcohol such as ethanol,1-propanol or 2-propanol; an anionic surface active agent such as afatty acid salt or an alkylsulfate ester; or a nonionic surface activeagent such as acetylene glycol, a polyoxyethylene alkyl ether or apolyoxyethylene fatty ester. From the viewpoint of the quality of imagesprinted, the amount of the lower alcohol to be incorporated ispreferably in the range of 2 to 10% by weight, more preferably in therange of 2 to 6% by weight of the ink composition. The amount of thesurface active agent to be incorporated is preferably in the range of0.01 to 2% by weight of the ink composition.

The ink composition according to the present invention may furthercomprise a water-soluble polymer or resin, an anti-foaming agent, a pHmodifier, a mildew-proofing agent and the like, if necessary.

The ink composition of the invention can be produced in a conventionalmanner. For instance, the ink can be obtained by the following method:all of the components are thoroughly mixed and dissolved, and themixture is filtered under pressure through a membrane filter having ahole diameter of 0.8 micrometers, and then degased by using a vacuumpump.

The ink composition according to the present invention is particularlysuitable for use in the ink jet recording method in which an ink isejected through a fine pore as droplets to conduct recording. The inkcomposition of the invention can also be used for ordinary writingutensils, recorders, pen plotters and the like.

In the case of the ink jet recording method, it is possible to achieveexcellent image recording by adopting, in particular, a means in whichdroplets are ejected by utilizing the vibration of a piezoelectricdevice, or a means in which thermal energy is utilized.

Formation of Color Images

According to another preferred embodiment of the present invention,there is provided a method for producing color images, in which the inkcomposition comprising the compound (I) above described, and specificyellow and magenta ink compositions are used.

The yellow ink composition for use in this embodiment comprises as acolorant a compound represented by the above formula (II) or (III).Further, the magenta ink composition for use in this embodimentcomprises as a colorant a compound represented by the above formula(IV).

By using these ink compositions in combination, color images whosecolors are well reproduced can be formed. These ink compositions arehighly reproducible in their own colors, and, in addition to this, theyare excellent in reproducibility in red, green, blue and black colorswhich are obtained by superposing two of or all of the ink compositionsone over another.

In the formula (II), one or more hydrogen atoms in the phenyl ornaphthyl group represented by R⁴ or R⁵ may be substituted. Specificexamples of the substituent include hydroxyl group, --SO₃ M, --COOM,--PO₃ M₂ (where M is as defined above), an alkyl group (preferably aC₁₋₄ alkyl group), and an alkoxy group (preferably a C₁₋₄ alkoxy group).

In the formula (II), the alkyl group represented by R⁶ or R⁷ ispreferably a linear or branched C₁₋₃ alkyl group. The alkoxy grouprepresented by R⁶ or R⁷ is preferably a linear or branched C₁₋₄(preferably C₁₋₂) alkoxy group.

The alkyl group represented by R⁸ is preferably a linear or branchedC₁₋₃ alkyl group. The alkyl moiety of the hydroxyalkyl group representedby R⁸ is a linear or branched C₁₋₄ (preferably C₁₋₂) alkyl group.

Further, the alkyl moiety of the hydroxyalkyl group represented by R⁹ isa linear or branched C₁₋₄ (preferably C₁₋₂ ) alkyl group.

Specific preferable examples of the compound represented by the formula(II) include the following compounds (II-1) to (II-10): ##STR11##

The alkoxy group represented by R¹⁰ or R¹¹ in the formula (III) is alinear or branched C₁₋₄ (preferably C₁₋₂) alkoxy group.

Further, the alkyl group represented by R¹² or R¹³ is preferably alinear or branched C₁₋₄ alkyl group.

Specific preferable examples of the compound represented by the formula(III) include the following compounds (III-1) to (III-10): ##STR12##

The alkyl group represented by R¹⁴ in the formula (IV) is preferably alinear or branched C₁₋₄ alkoxy group.

Further, the halogen atom represented by R¹⁵ is preferably fluorine,chlorine, bromine or iodine. Furthermore, the alkyl group represented byR¹⁵ is preferably a linear or branched C₁₋₄ alkyl group.

The halogen atom represented by R¹⁷ or R¹⁸ is preferably fluorine,chlorine, bromine or iodine. Further, the alkyl group represented by R¹⁷or R¹⁸ is preferably a linear or branched C₁₋₄ alkyl group.

Specific preferable examples of the compound represented by the formula(IV) include the following compounds (IV-1) to (IV-10): ##STR13##

The ink composition comprising the compound (II), (III) or (IV) can beformulated and prepared in the same manner as in the case of the inkcomposition comprising the compound (I). According to the preferredembodiment of the present invention, in the case where an image will beformed by the ink jet printing method, the amount of the compound (II)or (III) to be incorporated into the ink composition is preferably about0.5 to 3.0% by weight, more preferably about 1.0 to 2.0% by weight ofthe ink composition. Further, in the case of the compound (IV), theamount thereof is preferably about 0.5 to 4.0% by weight, morepreferably about 1.0 to 3.0% by weight of the ink composition.

EXAMPLES

The present invention will now be explained more specifically byreferring to the following Examples. However, the present invention isnot limited to these examples.

Example A

Inks, each having the composition shown in Table 1 were prepared in aconventional manner. In the table, figures are in "% by weight" of theink composition and the balances are water.

                                      TABLE 1                                     __________________________________________________________________________                   Example A              Comparative Example A                   Formulation of Ink                                                                           1 2 3 4 5 6 7  8  9  10                                                                              1   2   3                               __________________________________________________________________________    Dye                                                                           (I-1)           8                                                                               6                                                                              4     2          1                                         (I-5)                1.5            1                                         (I-7)                  2.5                                                                             2                                                    (I-8)                      3.5                                                (I-9)                         6.5                                             (I-11)                           3                                            (I-14)                              1                                         C.I. Acid Blue 9                      3                                       C.I. Direct Blue 86                       4   3                               Ethylene glycol          10                                                   Diethylene glycol                                                                            40                                                                              30                                                                              10    15                                                                              17    15   10  10                                  Glycerol           5 3 4      8     5 5   5   5                               Diethylene glycol monobutyl ether                                                                        10                                                 Triethylene glycol monobutyl ether                                                                          12 10                                           Triethanolamine        1   1                                                  2-Pyrrolidone          3                                                      Thiodiglycol                        8         8                               Ethanol                4                                                      1-Propanol           6              3         3                               Surfynol 465*      1     0.8     1.5  1   1                                   Mildew-proofing agent                                                                            0.3                                                                             0.3                                                                             0.3                                                                             0.3          0.3 0.3                                 __________________________________________________________________________     *: Surfynol 465 (manufactured by Nisshin Kagaku Kabushiki Kaisha,             acetylene glycol surface active agent)                                   

Evaluation Test A

The ink compositions of Examples A1 to A10 and of Comparative ExamplesA1 to A3 were evaluated in terms of the following Tests A1 to A4, byusing the following printer and recording papers.

Printer

Printer (1): An ink jet printer having an on-demand-type ink jet head(diameter of nozzle: 35 micrometers, 48 nozzles) made on an experimentalbasis, which produces droplets by utilizing the vibration of apiezoelectric device to conduct recording; the printer can print animage under such conditions that the driving frequency is 5 kHz, thatthe voltage for driving the piezoelectric device is 25 V and that theresolution is 360 dots/inch.

Printer (2): Desk Writer 550C (manufactured by Hewlett Packard Corp.)

Recording Papers

(1) Coated paper NM for ink jet printing (manufactured by MitsubishiPaper Mills)

(2) Canon Dry (manufactured by Canon Hanbi)

(3) Xerox 4024 (manufactured by Xerox)

(4) Xerox P (manufactured by Fuji Xerox)

(5) Ricopy 6200 (manufactured by Ricoh)

Test A1: Color Reproducibility

A solid image (100% duty) was printed by the printer (1) on each of therecording papers (1) to (5) by using each of the inks of Examples andComparative Examples.

With respect to the solid image (3×3 cm) of each color, the color-scalevalues L*, a* and b* according to the color- difference indicatingsystem defined by CIE (Commision International de l'Eclairage) weremeasured by Macbeth CE-7000 spectrophotometer (manufactured by MacbethCorp.). The difference between the color-scale values measured and thecolor reference values of cyan according to ISO 2845-1975, shown belowwere obtained, and the color difference was calculated by the followingequation (i).

                  TABLE 2                                                         ______________________________________                                                    L*           a*     b*                                            ______________________________________                                        Color reference                                                                           53.9         -19.1  -54.2                                         values of cyan                                                                ______________________________________                                         ##EQU1##                                                                  

The average value of the color differences ΔE*ab's which were obtainedin terms of the images printed on the five recording papers is as shownin Table 3, and the color differences were evaluated in accordance withthe following standard. The color differences shown in Table 3 are thosevalues which were obtained in terms of the images printed by using theprinter (1). Almost the same values were obtained even in the case whereimages were printed by using the printer (2).

In the table:

All of the color differences ΔE*ab's of the images printed on the fiverecording papers are 20 or less: O

At least one of the color differences is more than 20 and 30 or less: ◯

Only one of the color differences is in excess of 30: Δ

Two or more of the color differences are in excess of 30: X

Test A2: Quality of Image

Alphabets and graphic images were printed by the printer (1) and (2) oneach of the recording papers (1) to (5) with the inks of Examples andComparative Examples. These images were visually observed, and evaluatedaccording to the following standard:

Non-blurred, sharp images having excellent quality: O

Scarcely-blurred, sharp images having good quality: ◯

Scarcely-blurred, but slightly lacked in sharpness: Δ

Remarkably-blurred or lacked in sharpness: X

Test A3: Water Resistance

The samples of the solid image printed on the recording paper (3) withthe printer (1), obtained in the Test A1 were dipped in tap water forone hour, pulled out, and dried spontaneously. With respect to thesesamples, the ΔE*ab's were obtained before and after the test in the samemanner as in Test A1, and the results were evaluated in accordance withthe following standard:

The remaining rate obtainable by the following equation (ii) is:

100-90%: O

90-75%: ◯

75-60%: Δ

60% or lower: X ##EQU2##

Test A4: Light Resistance

The samples of the solid image printed on the recording paper (3) withthe printer (1), obtained in the Test A1 were placed in a transparentplastic cello case, and allowed to stand under the sunlight for 30 days.With respect to these samples, the ΔE*ab was obtained before and afterthe test in the same manner as in Test 1, and evaluation was carried outin accordance with the following standard:

The remaining rate obtainable by the above equation (ii) is:

100-90%: O

90-75%: ◯

75% or lower: X

The results of the Tests 1 to 4 were as shown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________                      Ink                                                                                                         Comparative                                     Example A                     Example A                     Test Item         1  2  3  4  5  6  7  8  9  10 1  2  3                       __________________________________________________________________________    Test 1**  ΔE*.sub.ab                                                                      28.7                                                                             19.8                                                                             17.6                                                                             12.4                                                                             13.0                                                                             18.1                                                                             17.5                                                                             22.1                                                                             14.8                                                                             16.3                                                                             15.2                                                                             18.3                                                                             16.7                    Color Reproducibility                                                                   Average Value*                                                                Judgement                                                                             ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ⊚        Test 2**  (1)     ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚        Quality of Image                                                                        (2)     Δ                                                                          ◯                                                                    ⊚                                                                 ◯                                                                    ⊚                                                                 ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 Δ                                                                          Δ                           (3)     ◯                                                                    ⊚                                                                 ⊚                                                                 ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ◯                     (4)     ◯                                                                    ⊚                                                                 ⊚                                                                 ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ◯                     (5)     ◯                                                                    ⊚                                                                 ⊚                                                                 Δ                                                                          ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ◯           Test 3    Water Resistance                                                                      ⊚                                                                 ⊚                                                                 ⊚                                                                 ◯                                                                    ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 X  Δ                                                                          Δ                 Test 4    Light Resistance                                                                      ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 X  ◯                                                                    ◯           __________________________________________________________________________     *: The color differences in Test 1 are those values which were obtained i     terms of the images printed with the printer (1); almost the same values      can be obtained even in the case where images are printed with the printe     (2).                                                                          **: In Tests 1 and 2, the judgments on the images printed with the printe     (1) were equal to those on the images printed with the printer (2).      

Example B

Yellow, magenta and cyan inks, each having the composition shown in thefollowing Table 4 were prepared in a conventional manner.

In the table, figures are in "% by weight" of the ink composition andthe balances are water.

                                      TABLE 4                                     __________________________________________________________________________    Formulation of Ink   Example B1                                                                              Example B2                                                                              Example B3                                                                              Comparative Example        __________________________________________________________________________                                                       B1                         Yellow Dye                                                                           II-3          1.5                                                             III-5                   2                                                     III-10                            0.5                                         C.I. Acid Yellow 23                         1.8                        Magenta Dye                                                                          IV-5                                                                          IV-6                                                                          IV-9                                                                          C.I. Acid Red 52                                                       Cyan Dye                                                                             I-4                                                                           I-3                                                                           I-13                                                                          C.I. Acid Blue 9                                                       Diethylene glycol    40 37  30                                                Glycerol                       6  5   3.5                                                                              12 10  8  6   6   5                  2-Pyrrolidone                  5  5   5            5   5   5                  Thiodiglycol                             10 10  10                            Ethanol                        4  4   4                                       2-Propanol                               6  6   6                             Mildew-Proofing agent                                                                              0.3                                                                              0.3 0.3                                               __________________________________________________________________________    Formulation of Ink   Example B4                                                                              Example B5                                                                              Example B6                                                                              Comparative Example        __________________________________________________________________________                                                       B2                         Yellow Dye                                                                           II-2          1.5                                                             II-10                             0.9                                         III-3                   1.2                                                   C.I. Direct Yellow 86                       1                          Magenta Dye                                                                          IV-1             2                                                            IV-4                                 0.9                                      IV-10                      1.5                                                C.I. Direct Red 9                               3                      Cyan Dye                                                                             I-4                               1                 1                         I-11                              3                 3                         I-3                                      2                                    I-15                 3                                                 Ethylene glycol                12 12  7            12  8   7                  Polyethylene glycol #200                 13 10  8                             Glycerol             3  3   2            10 10  10                            Triethanolamine                       1                    1                  N-Methyl-2-pyrrolidone         3  2.5 2            3   2.5 2                  1,3-Dimethyl-imidazolidinone                                                                       1  1   1                      5   5   5                  Ethanol                                  8  8   8                             1-Propanol                                                                    Mildew-Proofing agent          0.3                                                                              0.3 0.3                                                                              0.3                                                                              0.3 0.3                                                                              0.3 0.3 0.3                __________________________________________________________________________    Formulation of Ink   Example B7                                                                              Example B8                                                                              Example B9                                                                              Comparative Example        __________________________________________________________________________                                                       B3                         Yellow Dye                                                                           II-8          1.4                                                             III-5                   1                                                     III-7                             1.6                                         C.I. Acid Yellow 23                         1.2                        Magenta Dye                                                                          IV-1                       1.7                                                IV-8             2                                                            IV-9                                 2                                        C.I. Acid Red 249                               1.4                    Cyan Dye                                                                             I-1                                      4.5                                  I-3                            3.5                                            I-16                 4                                                        C.I. Direct Blue 86                                 2.5                Diethylene glycol    15 13  10 18 15  12           18  16  12                 Glycerol                                 10 10  8                             Diethylene glycol monobutyl ether                                                                  15 15  15                                                Triethylene glycol monobutyl etyher                                                                          8  8   8            8   8   8                  Dipropylene glycol monomethyl ether      5  5   5                             Surfynol 465                   1  1   1  0.1                                                                              0.1 0.1                                                                              1   1   1                  Mildew-Proofing agent                                                                              0.3                                                                              0.3 0.3                                                                              0.3                                                                              0.3 0.3                                                                              0.3                                                                              0.3 0.3                                                                              0.3 0.3 0.3                __________________________________________________________________________    Formulation of Ink   Example B10                                                                             Example B11                                                                             Example B12                                                                             Comparative Example        __________________________________________________________________________                                                       B4                         Yellow Dye                                                                           II-3          0.5                                                             III-8         0.5                 3                                           III-10                  1.8                 1.8                        Magenta Dye                                                                          IV-5             2.2                 4                                        IV-9                       2.5                                                C.I. Acid Red 289                               1.5                    Cyan Dye                                                                             I-4                  5                   8                                    I-13                           4                                              C.I. Direct Blue 199                                3                  Diethylene glycol    20 17  12 10 10  10           10  10  10                 1,5-Pentane diol                         8  8   8                             1,2,6-Hexane triol   3  3   3                                                 Glycerol                                 2  2                                 2-Pyrrolidone                  6  5   2.5          6   6   3                  Triethanolamine             1         1                    1                  2-Propanol           3.5                                                                              3.5 3.5                                               Surfynol 465                   1.5                                                                              1.5 1.5                                                                              2  2   2  1.5 1.5 1.5                Duck Algin NSPL (Kibun Pood Chemifa K.K.)**                                                                            0.005                                                                            0.005                                                                             0.005                         Mildew-Proofing agent                                                                              0.3                                                                              0.3 0.3                                                                              0.3                                                                              0.3 0.3                                                                              0.3                                                                              0.3 0.3                                                                              0.3 0.3 0.3                __________________________________________________________________________     *: Acetylene glycol surface active agent                                      **: Sodium alginate (watersoluble polymer)                               

Evaluation Test B

The inks of Examples B1 to B12 and of Comparative Examples B1 to B4 wereevaluated in terms of the following Tests B1 to B3, with the aboveprinter and recording papers.

Test B1: Color Reproducibility

Solid images (100% duty) of yellow, magenta, cyan, red, green, blue andblack were printed with the above printer (1) on each of the recordingpapers (1) to (5) with the inks of Examples and Comparative Examples.The image of red was obtained by superposing the yellow and magenta inksone over the other; the image of green was obtained by superposing theyellow and cyan inks one over the other; the image of blue was obtainedby superposing the magenta and cyan inks one over the other; and theimage of black was obtained by superposing the yellow, magenta and cyaninks one over another.

With respect to the solid image (3×3 cm) of each color, the color-scalevalues L*, a* and b* according to the color- difference indicatingsystem defined by CIE (Commision International de l'Eclairage) weremeasured by a Macbeth CE-7000 spectrophotometer (manufactured by MacbethCorp.). The differences between the color-scale values measured and thecolor reference values according to ISO 2845-1975, shown in Table 5 wereobtained, and the color difference was calculated by the above equation(i).

                  TABLE 5                                                         ______________________________________                                        Color reference values of each color (ISO 2845-1975)                              yellow    magenta cyan   red  green  blue black                           ______________________________________                                        L*  90.7      48.4    53.9   47.4 47.6   19.2 28.6                            a*  -18.4     78.1    -19.1  70.3 -74.1  35.5 0.1                             b*  91.1      -7.1    -54.2  47.5 23.2   -53.0                                                                              -2.5                            ______________________________________                                    

The average value of the color differences ΔE*ab's which were obtainedin terms of the images printed on the papers (1) to (5) was as shown inTable 6. The color reproducibility was evaluated in accordance with thefollowing standard.

All of the color differences ΔE*ab's obtained in terms of the images ofred, green, cyan and black are 20 or less: O

At least one of the color differences is more than 20 and 30 or less: ◯

At least one of the color differences is in excess of 30:X

The results were as shown in Table 6.

Further, the same test was carried out with the printer (2), and almostthe same results as the above were obtained.

Test B2: Water Resistance

The samples of the solid image printed on the recording paper (3),obtained in the Test B1 were dipped in tap water for one hour, pulledout, and dried spontaneously. With respect to these samples, the ΔE*abwas obtained before and after the test in the same manner as in Test B1,and evaluation was carried out in accordance with the followingstandard:

The remaining rate obtainable by the above equation (ii) is:

100-80% in all of the samples of seven colors: O

80-60% in all of the samples of seven colors: ◯

60% or lower in at least one of the samples of seven colors: X

Test B3: Light Resistance

The samples of the solid image printed on the recording paper (3),obtained in the Test B1 were place in a transparent plastic cello case,and allowed to stand under the sunlight for 30 days. With respect to thesamples, the ΔE*ab was obtained before and after the test in the samemanner as in Test B1, and evaluation was carried out in accordance withthe following standard:

The remaining rate obtainable by the above equation (ii) is:

100-90% in all of the samples of seven colors: O

90-75% in all of the samples of seven colors: ◯

75% or lower in at least one of the samples of seven colors: X

                                      TABLE 6                                     __________________________________________________________________________               Test                                                                          Test B1 Color Reproducibility Test 2B                                                                            Test 3B                                    ΔE*.sub.ab (Average value in 5 types of recording                       papers)                       Water                                                                              Light                           Formulation of Ink                                                                       Yellow                                                                            Magenta                                                                            Cyan                                                                             Red                                                                              Green                                                                             Blue                                                                             Black                                                                            Judgement                                                                          Resistance                                                                         Resistance                      __________________________________________________________________________    Example 1  17.5                                                                              16.7 24.6                                                                             13.6                                                                             17.5                                                                              26.8                                                                             4.9                                                                              ◯                                                                      ⊚                                                                   ⊚                Example 2  19.8                                                                              17.2 19.4                                                                             18.2                                                                             19.1                                                                              18.6                                                                             8.0                                                                              ⊚                                                                   ⊚                                                                   ⊚                Example 3  3.2 14.5 13.1                                                                             14.8                                                                             19.3                                                                              22.7                                                                             22.4                                                                             ◯                                                                      ⊚                                                                   ⊚                Example 4  15.3                                                                              18.0 17.7                                                                             19.6                                                                             18.8                                                                              19.3                                                                             19.7                                                                             ⊚                                                                   ⊚                                                                   ⊚                Example 5  8.5 12.2 18.1                                                                             18.0                                                                             16.2                                                                              13.0                                                                             17.3                                                                             ⊚                                                                   ⊚                                                                   ⊚                Example 6  5.7 11.8 12.8                                                                             20.9                                                                             14.4                                                                              12.4                                                                             20.8                                                                             ◯                                                                      ⊚                                                                   ⊚                Example 7  11.7                                                                              19.2 16.5                                                                             15.2                                                                             17.6                                                                              17.2                                                                             10.2                                                                             ⊚                                                                   ⊚                                                                   ⊚                Example 8  10.0                                                                              17.0 15.6                                                                             19.4                                                                             14.6                                                                              16.7                                                                             7.3                                                                              ⊚                                                                   ⊚                                                                   ⊚                Example 9  16.9                                                                              16.4 18.0                                                                             18.1                                                                             19.2                                                                              17.1                                                                             3.8                                                                              ⊚                                                                   ⊚                                                                   ⊚                Example 10 7.4 16.7 18.3                                                                             15.3                                                                              8.0                                                                              11.6                                                                             10.4                                                                             ⊚                                                                   ⊚                                                                   ⊚                Example 11 12.0                                                                              18.3 16.9                                                                             19.3                                                                             15.0                                                                              14.2                                                                             4.8                                                                              ⊚                                                                   ⊚                                                                   ⊚                Example 12 23.2                                                                              20.4 28.8                                                                             15.6                                                                             17.8                                                                              26.3                                                                             3.3                                                                              ◯                                                                      ⊚                                                                   ⊚                Comparative Example 1                                                                    7.4 21.3 15.7                                                                             32.1                                                                             36.3                                                                              41.2                                                                             30.4                                                                             X    X    X                               Comparative Example 2                                                                    19.8                                                                              15.3 18.4                                                                             30.6                                                                             18.8                                                                              39.3                                                                             28.7                                                                             X    X    X                               Comparative Example 3                                                                    7.0 13.9 15.2                                                                             28.4                                                                             19.7                                                                              40.9                                                                             35.0                                                                             X    X    X                               Comparative Example 4                                                                    12.1                                                                              24.8 16.7                                                                             33.8                                                                             27.9                                                                              45.1                                                                             42.6                                                                             X    X    X                               __________________________________________________________________________     *: The values shown in the table are those obtained in terms of the image     printed with printer (1). However, almost the same values were obtained       even in the case where images were printed with the printer (2).         

What is claimed is:
 1. An ink set comprising yellow, magenta and cyanink compositions, whereinthe cyan ink composition comprises as acolorant the compound represented by the formula (I): ##STR14## whereinX represents an ion of a metal selected from the group consisting of Cu,Fe, Co and Ni, M represents hydrogen atom, an alkali metal, ammonium oran organic amine, R¹ represents hydrogen atom or an alkyl group whichmay be substituted, Z represents --OH, --COOH or NR² R³ where R²represents hydrogen atom or an alkyl group which may be substituted, andR³ represents an alkyl group which may be substituted, or phenyl groupwhich may be substituted, n represents an integer of 1 to 15, k and leach independently represent 0 or 1, and m represents an integer of 1 to4, provided that k, l and m fulfill the inequality 2≦k+l+m≦4, b) theyellow ink composition comprises as a coloranti) a compound representedby the formula (II): ##STR15## wherein R⁴ and R⁵ each independentlyrepresent --OH, or --SO₃ M, or phenyl or naphthyl group substituted with--COOM, R⁶ and R⁷ each independently represent hydrogen atom, an alkylgroup or an alkoxy group, R⁸ represents hydrogen atom, an alkyl group ora hydroxyalkyl group, R⁹ represents hydrogen atom, --OH or ahydroxyalkyl group, and M is as defined in the above formula (I); orii)a compound represented by the formula (III): ##STR16## wherein R¹⁰ andR¹¹ each independently represent hydrogen atom, --OH or an alkoxy group,R¹² and R¹³ each independently represent hydrogen atom or an alkylgroup, and M is as defined in the above formula (I), and c) the magentaink composition comprises as a colorant a compound represented by theformula (IV): ##STR17## wherein R¹⁴ represents hydrogen atom or an alkylgroup, R¹⁵ represents hydrogen atom, a halogen atom or an alkyl group,R¹⁶ represents --COOH or --SO₃ ⁻, R¹⁷ and R¹⁸ each independentlyrepresent hydrogen atom, a halogen atom, an alkyl group or --SO₃ M, andM is as defined in the above formula (I).
 2. The ink set according toclaim 1, whereinthe cyan ink composition comprises water, awater-soluble organic solvent, and from 1.5 to 8.0% by weight of thecompound represented by the formula (I), the yellow ink compositioncomprises 0.5 to 3.0% by weight of the compound represented by theformula (II) or (III), and the magenta ink composition comprises from0.5 to 4.0% by weight of the compound represented by the formula (IV).3. A method for forming a color image comprising the step of ejectingdroplets of yellow, cyan and magenta ink compositions on a recordingmedium to form thereon a color image, whereina) the cyan ink compositioncomprises as a colorant a compound represented by the formula (I):##STR18## wherein X represents an ion of a metal selected from the groupconsisting of Cu, Fe, Co and Ni, M represents hydrogen atom, an alkalimetal, ammonium or an organic amine, R¹ represents hydrogen atom or analkyl group which may be substituted, Z represents --OH, --COOH or NR²R³ where R² represents hydrogen atom or an alkyl group which may besubstituted, and R³ represents an alkyl group which may be substitute,or phenyl group which may be substituted, n represents an integer of 1to 15, k and l each independently represent 0 or 1, and m represents aninteger of 1 to 4, provided that k, l and m fulfill the inequality2≦k+l+m≦4, b) the yellow ink composition comprises as a coloranti) acompound represented by the formula (II): ##STR19## wherein R⁴ and R⁵each independently represent --OH, or --SO₃ M, or phenyl or naphthylgroup substituted with --COOM, R⁶ and R⁷ each independently representhydrogen atom, an alkyl group or an alkoxy group, R⁸ represents hydrogenatom, an alkyl group or a hydroxyalkyl group, R⁹ represents hydrogenatom, --OH or hydroxyalkyl group, and M is as defined in the aboveformula (I); orii) a compound represented by the formula (III):##STR20## wherein R¹⁰ and R¹¹ each independently represent hydrogenatom, --OH or an alkoxy group, R¹² and R¹³ each independently representhydrogen atom or an alkyl group, and M is as defined in the aboveformula (I), and c) the magenta ink composition comprises as a coloranta compound represented by the formula (IV): ##STR21## wherein R¹⁴represents hydrogen atom or an alkyl group, R¹⁵ represents hydrogenatom, a halogen atom or an alkyl group, R¹⁶ represents --COOH or --SO₃⁻, R¹⁷ and R¹⁸ each independently represent hydrogen atom, a halogenatom, an alkyl group or --SO₃ M, and M is as defined in the aboveformula (I).
 4. The method according to claim 3, wherein the cyan inkcomposition comprises water, a water-soluble organic solvent, and from1.5 to 8.0% by weight of a phthalocyanine derivative represented by theformula (I) .
 5. The method according to claim 3, herein the color imageincludes a color of red, green or blue which is formed by superposingtwo of the ejected ink compositions selected from the group consistingof the yellow, cyan and magenta ink compositions.
 6. The methodaccording to claim 3, wherein the color image includes a color of blackwhich is formed on the recording medium by superposing the ejectedyellow, cyan and magenta ink compositions.
 7. The method according toclaim 3, whereinthe cyan ink composition comprises 1.5 to 8.0% by weightof the phthalocyanine derivative represented by the formula (I); theyellow ink composition comprises 0.5 to 3.0% by weight of the compoundrepresented by the formula (II) or (III), and the magenta inkcomposition comprises 0.5 to 4.0% by weight of the compound representedby the formula (IV).